1. Field of the Invention
The invention relates to a transport unit for conveying items to a scanning unit of a self-service cash register system, with a belt conveyor to transport the item in a transport direction and with a marking unit to identify placement areas on an item placement surface of the belt conveyor open for placing items.
2. Discussion
The invention further relates to a method for dividing an item placement surface of a belt conveyor of a transport device for transporting items into a plurality of placement areas open for placing items, arranged one behind the other in a transport direction of the transport unit, where the individual placement areas are identified by means of a marking unit.
Self-service cash register systems are in increasing use in retail to identify the items selected by a customer largely automatically and to calculate the bill for the purchase. To do this, the items are usually optically recorded contactlessly with the help of a scanning unit as one surface of the items is scanned and a marking specifically serving to identify the item is recorded.
In order to ensure reliable scanning of the entire surface of the item, a device known as a tunnel scanner is used as a scanning unit, for example. The items are conveyed automatically to the tunnel scanner, typically over a transport unit having a belt conveyor. The tunnel scanner has a plurality of scanning modules that are attached to a frame arranged in the shape of an archway over the belt conveyor. With the help of the scanning modules, the entire surface of the item is scanned, with the exception of a contact side on which the items are lying on an item placement surface of the belt conveyor. The items deposited manually by the customer on the item placement area are typically not oriented in any particular way. A further scanning module can be arranged below the belt conveyor for optical scanning of the items in such manner that the contact surface of the items can also be optically detected through a recess in the transport unit.
In order to ensure a high degree of automation and a low error rate, the items to be recorded are conveyed sequentially to the scanning unit. For this purpose, for example, it is known from DE 102 35 865 A1 to assign marking units to the belt conveyor by means of which the item placement surface formed by the slack side of the belt conveyor can be divided into a plurality of placement areas of a specified size. The customer is requested to deposit only one item in each placement area on the belt conveyor. This method ensures that the items can be conveyed to the scanning unit spaced apart and be identified reliably. The limits of the individual deposit areas are highlighted visually, for example, by means of the marking unit. The disadvantage is that the placement areas are of a constant, pre-defined size, which is also determined by the design. The placement areas cannot be adapted to the size of the item assigned to them. The fault lies with the rigid assignment of the marking unit to the belt conveyor. In this respect, the spacing of the individual items is unnecessarily large, particularly with a small-sized item, and limits the flow of items. In contrast, very large items in particular can project beyond the limits of the placement areas.